Generally, arrays of electronic devices such as semiconductor dice are held securely in position on adhesive surfaces, for instance, after they have been singulated from a sheet of wafer. There are many types of commercially available adhesive surfaces, commonly in the form of adhesive films. However, there are also adhesive surfaces in the form of gel. Gel-Pak® provides an example of a receptacle for dice with an adhesive surface made up of a thin, flexible and adhesive gel membrane. The adhesive gel membrane is supported on a mesh with a non-adhesive side in contact with the mesh. An adhesive side of the gel membrane holds the dice securely. To detach a die from the membrane, vacuum is applied on the non-adhesive side of the gel membrane such that the gel membrane is deformed and conforms to the shape of the mesh. The die is partially detached from the gel membrane as a result of vacuum force on the membrane. Thus, the area of contact between the gel membrane and the die is reduced. The die can usually be removed completely from the gel membrane thereafter by a pick-up tool such as a collet of a die bonder by applying a vacuum suction force on the partially detached die through the collet.
Nevertheless, in cases when the dimensions of a die are as small as 300 μm by 400 μm, the die provides limited area for vacuum suction of the collet to act upon and pick up the die from the adhesive membrane. The problem is worse when the die is placed on very adhesive surface such as that provided by Gel-Pak® if the downward adhesive force on the die is larger than the upward vacuum force on the die from the collet.
Unlike film-based adhesive surfaces, ejector pins cannot be applied on the underside of the film holding the die by pushing the die upwards at specific points on the die, which helps to partially peel the die off from the adhesive surface. Such a method cannot be used when the dice are mounted on adhesives like Gel-Pak® since the space under the die is blocked by a container for the gel. Thus, the only way to remove the firmly-adhered dice may be to manually peel the dice off from the adhesive surface by using a tool such as a pair of tweezers. This manual method of removing dice is both tedious and time consuming when there is a large number of dice to be removed. Therefore, it would be desirable to devise an automated method for detaching dice from adhesive surfaces even where an initial adhesion force is larger than the pick-up force generated by vacuum suction.